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Difference between NAS level congestion control and APN based congestion control ?

+5 votes

when to use what ?

posted Oct 18, 2014 by Harshita

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1 Answer

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NAS Level Congestion Control
Ø When the network detects EMM signalling congestion, it may perform NAS level congestion control. The NAS level congestion control consists of general NAS level mobility managementcontrol and subscribed APN based congestion control
Ø Under general overload conditions the network may reject mobility management signalling requests from UEs. The network should not reject requests for emergency bearer services and requests from high priority users
Ø When general NAS level mobility management control is active, the network may prioritize rejecting messages that has the NAS signalling low priority indicator before rejecting messages without the NAS signalling low priority indicator
Ø When the NAS level congestion control is active in mobility management, the network may include a value for the back-off timer (T3346) in the reject messages
Ø If the UE enters a new PLMN which is not in the list of equivalent PLMNs, it shall stop timerT3346 when initiating mobility management procedures in the new PLMN
Ø When subscribed APN based congestion control is active for a particular APN, the network may reject attach request from UEs with a subscription to this APN
Ø A UE configured for NAS signalling low priority indicates this by including the Device propertiesIE in the appropriate NAS message and setting the low priority indicator to "MS is configured for NAS signalling low priority"
Ø The UE shall set the low priority indicator to "MS is not configured for NAS signalling low priority" for the following cases
· The UE has a PDN connection for emergency bearer services established or is establishing a PDN connection for emergency bearer services
· The UE is accessing the network with access class 11 – 15
· The UE responds to paging
Reference: 3GPP TS 24.301

answer Jul 24, 2016 by anonymous
Similar Questions
0 votes

When the MME sends a DL NAS message is the connection between MME and UE held long enough just to receive the message ? What happens if there are back-to-back NAS messages to be delivered, does the the UE open a connection to MME and receive all the messages at once. Or does it open close the connection to get each of the messages separately.

+5 votes

Uplink NAS transport message is used between eNodeB and MME to pass NAS messages between UE and MME transparently.
Since eNodeB has already communicated TAI and E-CGI as part of "Initial UE message" and MME knows current serving (cell and tai ) of UE then why both IEs are mandatory in Uplink NAS transport. I think it should be optional and it should be included in the message when there is a change in serving (cell or tai or both).

+1 vote

In which cases/scenarios, an UE would maintain multiple active NAS connection with the different serving networks ?

+1 vote

128-bit Counter blocks (Tn, n=0,1...) are constructed in order to, e.g. cipher/decipher NAS messages. Each T block contains a sequence number, an overflow counter and a 64-bit zone also used as counter.
Altogether, there are three "counting" fields in each T block.
How/when each one of these three fields is: initialized, reset and managed/increamented during time?
What happens to each field when a new NAS message is received?

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